This invention relates to the fabrication of metallic articles from precursor materials, and, more particularly, to the fabrication of such articles from collated sheets of metals of varying compositions.
Historically, most structural articles made of metallic alloys have been prepared by either casting to shape or casting and then deforming to shape, followed by a final metalworking in some cases. These approaches, while successful for many applications and widely used, typically leave the final article with a degree of internal compositional uncontrollability. Such uncontrolled compositional variation is one of the major causes of premature failure or inefficiency in the use of materials to avoid premature failure.
Some metallic articles are desirably fabricated with compositions that are either controllably homogeneous or controllably inhomogeneous on a microscopic or macroscopic level, at a level of control not possible with conventional casting or deformation processing. In response to this need, a wide variety of sophisticated fabrication technologies have been developed. These include, for example, powder processing techniques wherein powders of a metallic composition are placed into a form and heated and/or forged to a near net shape, often accompanied by homogenizing and other heat treatments.
The available techniques are limited in their ability to achieve controlled compositions and microstructures. Powder techniques cannot be readily used, for example, to produce an article whose composition varies in a regular, controllable manner on a local microscopic scale, nor articles whose composition varies in a regular, controllable manner on a macroscopic scale across the dimensions of the article. Such variations are desirable in a number of types of finished articles, where a graded structure would be desirable or where the required properties vary from location to location.
There is a need for an approach which provides greater control over the composition of the article both on a microscopic level and a macroscopic level. The present invention fulfills this need, and further provides related advantages.